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HUTTONIAN THEORY. 



J37 



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completely obliterated, while in others they re- 

 main entire. It is thus that veined granite^ or 

 what I think ihould be called granitic fchiftus, 

 often graduates into granite in mafs\ that is, gra- 



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nite without any fchiftofe or fiffile texture. 

 Sauflure fays, that to be veined or not vein- 

 ed, is an afiedion of granite, that feems, in ma- 

 ny cafes, accidental * y as, in the midfl of rocks 

 of that fubllance, moll clearly fiffile, large por- 

 tions appear without any veftige of ftratifica- 

 tion. Of this phenomenon, which is frequent 

 in the Alps, inftances are alfo to be met with 

 in the granite rocks of Scotland, and the adja- 

 cent ifles ; and I know that Dr Hope, in a mi- 

 neraloglcal excurfion which he lately made 



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among the Hebrides, obierved many interefting 

 and curious examples of it. Indeed, when 



fo much fufed as to cryftallize, 



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rocks 



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.,at ^.'°i!' and fo comprefled, at the fame time, as to 



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main ftratified, they were evidently on the 

 verge of change ; two oppolite forces were very 

 nearly balanced, and each carried as far as it 

 could go without entirely overcoming the other ; 

 io that a frnall alteration in the conditions may 

 5' liave made a great alteration in the effeds. 

 Hence a fudden tranfition from a ftratified to 



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Voyages aux Alpes, tonj. iv. § 2143 



'Arttl .. 



